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Copyright (c) 2014 Jennifer M. Francis, Joonhee Lee, Lily M. Wang.

Abstract

Building services equipment often produces noise signatures with significant tones in them that can lead to complaints in the built environment. Previous studies have investigated prominence levels of assorted tonal frequencies, but it is still unclear what prominence of the tones across varying tonal frequencies can lead to human annoyance. This project seeks to apply two different methods towards defining annoyance thresholds of tones in noise at two tonal frequencies: 125 Hz and 500 Hz. In the first, subjects are asked to perform a task, while exposed to ten minutes of a broadband noise spectrum with a specific level of tonal prominence. They are subsequently asked to rate their annoyance to that noise condition. Five prominence levels of each of the two tones are tested above two different background noise levels, for a total of 20 test trials. In the second methodology, subjects listen to each of the two tonal frequencies at a predetermined level above each of the two background noise levels, and then adjust the level of the tone up or down until it becomes just annoying. The strengths, weaknesses, and results obtained for the annoyance thresholds of tones in noise from each of these methods are compared.